Silver-deposited catalyst for production of ethylene oxide

Abstract

A silver-deposited catalyst for production of ethylene oxide by oxidizing ethylene, having high selectivity and long life, is provided by this invention. The catalyst is characterized by a combination of (a) catalyst ingredients comprising silver and a cation component selected at least from sodium, potassium, rubidium and cesium, and (b) a carrier composed mainly of alpha-alumina, said carrier having a surface area of 0.6 to 2 m2/g, a water absorption of 20 to 50%, a silica content of 0.5 to 12% by weight, a silica content, per m2/g of surface area, of 0.5 to 12, preferably 1 to 8, and a sodium content of 0.08 to 2% by weight.

What is claimed is: 
     
       1. A silver-deposited catalyst for production of ethylene oxide by oxidizing ethylene, said catalyst comprising as catalyst ingredients silver and a cation component selected at least from sodium, potassium, rubidium and cesium, and a carrier composed mainly of alpha-alumina, said carrier having: (1) a surface area of 0.8 to 2m 2  /g,   (2) acidity that can be detected by an indicator having a pKa of +4.8,   (3) a water absorption of 20 to 50%,   (4) a silica content of 0.5 to 12% by weight,   (5) a silica cointent, per m 2  /g of surface area, of 0.5 to 12 % by weight,   (6) a sodium content of 0.08 to 2% by weight, and   (7) a crystal of Al 6  Si 2  O 13  which can be detected by X-ray diffraction analysis.   
     
     
       2. The catalyst of claim 1 wherein the cation component is composed of (A) sodium and (B) at least one of potassium, rubidium and cesium. 
     
     
       3. The catalyst of claim 1, wherein the cation component is composed of (A) sodium, (B) at least one of potsassium, rubidium and cesium and (C) barium. 
     
     
       4. The catalyst of claim 1 wherein the cation component has been deposited on the carrier from aqueous solution. 
     
     
       5. The catalyst of claim 1, wherein during production of said catalyst, silver and/or the cation component is impregnated in the carrier and heat-treated in super-heated steam at 130° to 300° C. 
     
     
       6. The catalyst of any one of claims and 1 and 2 to 5 wherein the carrier has a surface area of 0.8 to 1.7 m 2  /g. 
     
     
       7. The catalyst of any one of claims 1 and 2 to 5 wherein the carrier has an average pore diameter of 0.9 to 3.5 micrometers. 
     
     
       8. The catalyst of any one of claims 1 and 2 to 5 wherein the carrier has a silica content of 1 to 12% by weight. 
     
     
       9. The catalyst of claim 6 wherein the carrier has an average pore diameter of 0.9 to 3.5 micrometers. 
     
     
       10. The catalyst of claim 6 wherein the carrier has a silica content of 1 to 13% by weight. 
     
     
       11. The catalyst of claim 7 wherein the carrier has a silica content of 1 to 12% by weight. 
     
     
       12. The catalyst of claim 1 wherein the carrier has a silica content, per m 2  /g of surface area, of 1 to 8% by weight.